Class 9 – Science   Chapter – 10 Work and Energy

Quiz -1 (1 Mark Questions)

Q-1 The formula to find the work done is

1. W = F+s
2. W = F.s
3. W = F-s
4. W = F/s

Ans – (b) W = F.s

Q-2 If 20 N of force is applied on a body and the body is displaced by 2 m, then work done on the body is

(a) 5 J

(b) 40 J

(c)10 N

(d) 40 N

Ans – (b) 40 J

Q-3 If a force acting on a body causes no displacement, the work done is—————

1. -1
2. 1
3. 0
4. Infinity

Ans – (c) 0

Q-4 Objects in motion possess energy and can do work; this energy is called———————

1. Solar energy
2. Thermal energy
3. Potential energy
4. Kinetic Energy

Ans – (d) kinetic energy

Q- 5 Which of the following is NOT a stored form of energy?

(a) Chemical energy

(b) Gravitational potential energy

(c) Kinetic energy

(d) Elastic potential energy

Ans – (c) Kinetic energy

Q-6 The sum of kinetic energy and potential energy is ————-

1. Mechanical energy
2. Thermal energy
3. Potential energy
4. Kinetic Energy

Ans – (a) Mechanical energy

Q-7 1 kilowatt =

1. 1 watt
2. 10 watts
3. 100 watts
4. 1000 watts

Ans – (d) 1000 watts

Q-8 If the force applied on a body displaces it in the opposite direction, then the work done on the body by the applied force is _______

(a) is negative.

(b) is positive.

(c) is zero.

(d) can be positive or zero.

Ans – (a) is negative

Q-9 The ratio of change in the kinetic energy of a body to the time taken by the body for the change in energy is equal to the

(a) pressure applied by the body.
(b) work done on the body.

(c) energy stored in the body.

(d) power expended by the body

Ans – (d) power expended by the body

Q-10 The energy used in one hour at the rate of 1kW is known as ————-

1. 10kWh
2. 1kWh
3. 1W
4. 1kW/h

Ans – (b) 1 kWh

Q-11 What are the various factors affecting kinetic energy?

1. Mass
2. Momentum
3. Velocity
4. All the above options

Ans – (d) all the above options

Q-12 When two identical bodies are in motion, the body with a higher velocity has ————-

1. Lower Kinetic Energy
2. Higher Kinetic Energy
3. No Kinetic Energy
4. None of the options

Ans – (b) Higher kinetic energy

Q-13 If the displacement is perpendicular to the force, then the work done is said to be—————.

1. -1
2. 1
3. 0
4. Infinity

Ans – (c) 0

Q-14  The unit of work is joule. The other physical quantity that has same unit is

(a) power         (b) velocity         (c) energy         (d) force

Ans – (c) energy

Q-15 The spring will have maximum potential energy when

(a) it is pulled out         (b) it is compressed

(c) both (a) and (b)         (d) neither (a) nor (b)

Ans – (c) both (a) and (b)

Q-16 The energy possessed by an oscillating pendulum of a clock is

(a) kinetic energy         (b) potential energy

(c) restoring energy.         (d) mechanical energy

Ans – (d) mechanical energy

Q-17 A player transfers a momentum of 12 kg m/s to a ball of mass 400 g which is at rest. Find the work done on the ball.

(a) 180 J

(b) 345 J

(c) 400 J

(d) 427 J

Ans – (a) 180 J

Q-18 The gravitational potential energy of an object is due to

(a) its mass

(b) its acceleration due to gravity

(c) its height above the earth’s surface

(d) all of the above.

Ans – (b) its acceleration due to gravity

Q-19 A ball is dropped from a height of 10 m.

(a) Its potential energy increases and kinetic energy decreases during the falls

(b) Its potential energy is equal to the kinetic energy during the fall.

(c) The potential energy decreases and the kinetic energy increases during the fall.

(d) The potential energy is minimum and kinetic energy is maximum while it is falling.

Ans – (c) The potential energy decreases and the kinetic energy increases during the fall.

Q-20 If the velocity of a body is doubled its kinetic energy

(a) gets doubled         (b) becomes half

(c) does not change         (d) becomes 4 times

Ans – (d) becomes 4 times

Q-21 How much time will be required to perform 520 J of work at the rate of 20 W?

(a) 24s         (b) 16s         (c) 20 s         (d) 26 s

Ans – (d) 26 s

Q-22 A student carries a bag weighing 5 kg from the ground floor to his class on the first floor that is 2 m high. The work done by the boy is

(a) 1 J         (b) 10 J         (c) 100 J         (d) 1000 J

Ans – (c) 100 J

Q-23 One unit of electrical energy is equal to

(a) 3.6 x 105J         (b) 3.6 x 106J    (c) 36 x 105J         (d) both (b) and (c)

Ans – (b) 3.6 x 106J

Q-24 Which is the renewable source of energy among the following?

(a) Sun        (b) Coal            (c) Natural gas                 (d) Fossil fuels

Ans –  (a) Sun

Q-25 The energy of a body due to its motion is called  ____.

(a) gravitation energy

(b) static energy

(c) kinetic energy

(d) All of these

Ans – (b) static energy

Q-26 In the dams water is stored in the high reservoirs and then made to fall. This falling water then rotates the turbines to generate electricity. In this energy conversion process can you tell the initial and final energies respectively?

(a) Kinetic energy and electrical energy

(b) Potential energy and kinetic energy

(c) Potential energy and electrical energy

(d) Kinetic energy and potential energy

Ans – (b) Potential energy and kinetic energy

Q-27 A man of mass 50 kg jumps to a height of 1 m. His potential energy at the highest point is(g = 10 m/s2):

(a) 50 J

(b) 500 J

(c) 5 J

(d) 5000 J

Ans – (b) Potential energy and kinetic energy

Q-28 What is the work done on a satellite by the Earth’s gravitational force?

(a) zero, because the force exerted by the Earth on the satellite is parallel to the displacement of the satellite.

(b) zero, because the force exerted by the Earth on the satellite is perpendicular to the displacement of the satellite.

(c) positive, because the force exerted by the Earth on the satellite is perpendicular to the displacement of the satellite.

(d) negative, because the force exerted by the Earth on the satellite is perpendicular to the displacement of the satellite.

Ans – (b) zero, because the force exerted by the Earth on the satellite is perpendicular to the displacement of the satellite.

Q-29 Identify from the following which is true about work?

(a) Unit of work is newton metre

(b) Its SI unit is Joule.

(c) It is a scalar quantity

(d) All of these

Ans – (a) Unit of work is newton metre

Q-30 When a body like earth is moving in a circular path the work done in that case is zero because:

(a) Centripetal force acts in the direction of motion of the body

(b) Centripetal force acts along the radius of circular path

(c) Gravitational force acts along the radius of circular path

(d) Centrifugal force acts perpendicular to the radius of circular path

Ans –  (d) Centrifugal force acts perpendicular to the radius of circular path